1. Field of the Invention
The present invention relates to an information encoding apparatus and method for encoding a plurality of pieces of information, and an information re-encoding apparatus and method for re-encoding a plurality of pieces of first encoded information into a plurality of pieces of second encoded information.
2. Description of the Related Art
Recently, a storage capacity of optical discs (e.g., DVDs (Digital Versatile Discs)) and optomagnetic discs is increased, and the optical discs and the optomagnetic discs are used for recording moving pictures or the like.
FIG. 17 shows a conventional information encoding apparatus 1500.
The information encoding apparatus 1500 includes a storage section 1501, a scrambling section 1502 and a parity generation section 1503. The information encoding apparatus 1500 is included in, for example, an optical disc recording and reproduction apparatus for encoding a plurality of pieces of information.
The storage section 1501 stores a plurality of pieces of information.
The scrambling section 1502 scrambles the plurality of pieces of information. The plurality of pieces of information are scrambled in order to provide the optical disc recording and reproduction apparatus, for reproducing the plurality of pieces of information, with stable tracking servo control. The plurality of pieces of information are scrambled by adding a random data stream (hereinafter, referred to as a “scrambling pattern”) to the information.
For example, an optical disc has a plurality of tracks formed therein. Information is recorded on the plurality of tracks. A scrambling pattern to be added to the information at a prescribed position on a track is different from a scrambling pattern to be added to the information at a different position on the track. In general, different scrambling patterns are used for information of different error correction units.
The parity generation section 1503 generates a plurality of parities in correspondence with the plurality of pieces of scrambled information.
The plurality of pieces of scrambled information are respectively supplied with the plurality of parities, so that encoded information is generated.
The encoded information is recorded on a recording medium such as an optical disc or the like.
In the case where the information cannot be recorded at a prescribed position on the track due to a defect at that position, the information is recorded at a different position on the track. When the information is recorded at a different position, the scrambling pattern to be added to the information needs to be changed. Accordingly, the information needs to be re-encoded.
FIG. 18 illustrates re-encoding of information.
Hereinafter, a procedure for generating a plurality of pieces of information scrambled with a plurality of scrambling patterns C by re-encoding a plurality of pieces of information scrambled with a plurality of scrambling patterns B by the information encoding apparatus 1500.
The scrambling section 1502 de-scrambles the encoded information stored in the storage section 1501. For example, de-scrambling is an operation for returning scrambled information into the non-scrambled information. De-scrambling, similar to scrambling, is performed by adding a scrambling pattern to the scrambled information. For example, non-scrambled information is generated by adding a scrambling pattern B to the information scrambled with the scrambling pattern B.
The scrambling section 1502 generates information scrambled with a scrambling pattern C by adding the scrambling pattern C to non-scrambled information.
The parity generation section 1503 generates parities. The parity generation section 1503 generates re-encoded information by supplying information scrambled with the scrambling pattern C with a parity.
Re-encoding information using the information encoding apparatus 1500 is time-consuming. For example, for performing real-time recording of a moving picture, the recording rate is significantly reduced.
It has been proposed to reduce the information re-encoding time by dividing encoded information into a portion relying on the information to be recorded on a recording medium and a portion relying on the position on the recording medium at which the information is to be recorded, processing these portions, and adding these portions together when recording these portions on the recording medium (for example, Japanese Laid-Open Publication No. 2000-306342).
FIG. 19 shows a structure of an information re-encoding apparatus 1700 described in Japanese Laid-Open Publication No. 2000-306342.
The information re-encoding apparatus 1700 includes a first storage section 1701, a first parity generation section 1702, a pattern generation section 1703, a second storage section 1704, a second parity generation section 1705, and an addition section 1706.
The first storage section 1701 has a plurality of pieces of information stored thereon. The first parity generation section 1702 generates a plurality of first parities in correspondence with the plurality of pieces of information.
The plurality of pieces of information are respectively supplied with the plurality of first parities, so that a plurality of pieces of error correction encoded information are generated. The plurality of pieces of error correction encoded information are stored in the first storage section 1701.
The pattern generation section 1703 generates a plurality of scrambling patterns. The plurality of scrambling patterns are stored in the second storage section 1704.
The second parity generation section 1705 generates a plurality of second parities in correspondence with the plurality of scrambling patterns.
The plurality of scrambling patterns are respectively supplied with the plurality of second parities, so that a plurality of pieces of error correction encoded scrambling patterns are generated. The plurality of error correction encoded scrambling patterns are stored in the second storage section 1704.
The addition section 1706 generates encoded information by adding the plurality of pieces of error correction encoded information and the plurality of error correction encoded scrambling patterns. The encoded information is stored in a recording medium (not shown).
The above-described apparatuses have the following problems.
(1) The method of scrambling information to be recorded sector by sector of the recording medium is time-consuming.
(2) In the case where the information re-encoding time is reduced by dividing encoded information into a portion relying on the information to be recorded on a recording medium and a portion relying on the position on the recording medium at which the information is to be recorded, processing these portions, and adding these portions together when recording these portions on the recording medium, an additional storage section for temporarily storing the portion of the encoded information relying on the position on the recording medium at which the information is to be recorded is required.
(3) In the case where the information cannot be recorded at a prescribed position on the track and is recorded at a position which is not adjacent to the prescribed position, time is required for re-encoding the portion of the information relying on the position on the recording medium at which the information is to be recorded so that the information is recordable at a position which is not adjacent to the prescribed position.